Once saving a batch configuration with a password and username you can not remove it

Overview: Once saving a batch configuration with a password and username you can not remove it because username becomes a required field

Steps to Reproduce:

1. Log into some FOLIO environment as User X
2. Go to system settings->invoices->Batch group configuration
3. Choose a batch group
4. add a password and username
5. Click save
6. Try to remove the password and user name
7. click save

Expected Results: Password and username are save as blank

Actual Results: Settings can not be saved because username is a required field

Additional Information: before setting either of these fields user can save configuration with no credentials in these fields